Calendar heatmap generator
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Calendar heatmap
Show daily intensity over a calendar grid to reveal recurring patterns. Create a private, publication-ready calendar heatmap directly in your browser without transmitting sensitive rows off-device. Data is processed locally on your hardware with zero server uploads, enabling instant export to SVG, PNG, and Excel data.
Edit the data, then export.
Everything runs in your browser. Your data is not uploaded.
Data
Paste tab-separated data from Excel or edit the cells directly.
Paste or import table data
Paste a header row, or choose a local CSV/TSV file. Files are read in this browser and capped at 500 rows.
Appearance
Preview
Sample preview of the example data. The live chart takes over as soon as you start working.
SVG, PNG, and Excel exports are generated locally in this browser. PowerPoint export is temporarily unavailable while its dependency path is reviewed for a high-severity image parser advisory.
Visual Encoding & Comparative Anatomy
A calendar heatmap maps daily quantitative metrics into a traditional calendar grid composed of months and weekdays. Numerical intensity is encoded as color saturation or lightness within individual day cells, allowing you to instantly identify temporal trends like weekend drop-offs or seasonal clusters. All data parsing and rendering occurs entirely in your local browser environment—Trendalyzer never uploads your datasets to an external server.
Input Format & Required Columns
Format input columns for calendar heatmap with explicit headers and numerical measurements. Verify that rows represent discrete categories or observations without unformatted symbol artifacts.
Example Comparison Table
| Date | Commits |
Best Practices for Category Comparison
- Ensure sufficient visual distinction for calendar heatmap marks across standard and high-contrast viewports.
- Align text labels horizontally whenever possible to improve cognitive readability for calendar heatmap elements.
- Double-check scale boundaries and zero-anchors before exporting calendar heatmap presentation artwork.
- Data shape
- Date and numeric value columns
- Exports
- SVG, PNG, and Excel data; PowerPoint export is temporarily unavailable pending dependency review.
How it works
You edit a table in this page. The renderer draws an SVG from those rows in your browser, then you can download SVG, PNG, or Excel data. The table is not uploaded to any external processing server.
Frequently asked questions
Why are calendar charts effective for seasonality?
They immediately reveal weekday vs weekend patterns, holiday dips, and seasonal monthly clusters.
Related tools
Reviewed 16 August 2026.